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Anno 2020 Numero 4-5

Technology
April - May 2020

Operator protection in phytosanitary treatments

Crop protection uses products that are harmful, in many forms, to the human organism. It is, therefore, necessary to adopt and scrupulously apply the Personal Protective Equipment designed for this purpose

From floriculture and greenhouse horticulture to open field arboriculture. For their defense, all plant production requires phytosanitary treatments (whether traditional or organic). The products available on the market are basically in liquid or powdered form and distributed in a mixture with water employing sprayers coupled to the tractor or, for small areas, on the shoulder. 

The risks to which operators are exposed are those of ingestion, inhalation, and skin contact with the active ingredients used.  Contrary to what is assumed, it has been widely proven that contact with exposed parts of the skin of the body is the greatest danger of intoxication or even poisoning, both in the short and especially in the long term, even with the onset of severe diseases over time.

Personal Protective Equipment (PPE) is the primary protection measure to be considered for adequate personal protection. PPE is classified according to three levels of protection, namely: Cat. I: suited for conditions of minor physical risk; Cat. II:  for risk levels higher than Cat. I, but not serious; Cat. III, designed to protect the operator from serious and/or fatal risks.

With particular reference to the agricultural sector, in addition to PPE (by definition for personal use), protection from the chemical risk represented by phytosanitary products can be effectively implemented employing certain specific devices that may accompany the tractor cab, i.e., the operator's workstation. Therefore, from this point of view, a pressurized cab equipped with activated carbon chemical filters (approved in "class 4") can be a valid alternative to the classic PPE wearable in this context, i.e., overalls, gloves, boots, and respiratory protection devices.

 

Class 4 cabs

Approved in compliance with UNI 15695-1:2018, they provide for the installation of filters (certified for protection against the most common substances contained in the active ingredients of plant protection products), integrated into "enhanced" ventilation systems, able to establish and maintain slight pressurization of the cab over time, so as to prevent accidental infiltration of polluted air from the external environment.

Although the highest risk is that of contact, there is no doubt that a further route of possible intoxication of the operator in plant protection treatments may be that of inhalation of toxic products. Therefore, specific PPE has been developed, of different conformation, for the level of protection and body area covered by the device. 

Protection of the respiratory tract may be limited to physical filtration of the air, capable of retaining particles of different particle sizes so that they do not reach the airways. Conversely, chemical filtration, which protects against harmful gases or vapors, uses devices capable of blocking certain classes of substances, also depending on their concentration.

The most common devices for both physical and chemical airway protection are half-masks, masks, and air conditioning helmets.   The choice of the most suitable PPE depends on the adaptation to specific anatomical characteristics of the operator, especially in terms of adherence to their face and maintenance of the overpressure required for insulation from potential contact with harmful substances.

 

Masks and half-masks

They are either one or two-filter. Masks and half-masks, while providing excellent levels of protection and more freedom of movement than helmets, offer airway protection only, so they must be integrated with other PPE head protection such as disposable hoods or headgear. Their use by personnel with beards or sideburns is not recommended, as they may interfere with the correct adherence of the mask to the face.  Like helmets, masks usually have a forced ventilation system to ensure slight internal pressurization.

As the name suggests, the half-masks partially cover the face, in particular only the area of the nose and mouth. Therefore, for adequate protection, they must be combined with protective goggles and PPE to cover the head.   Particular attention must be paid to the protection of the forehead, which is a portion of the skin of significant extension exposed to direct contact with harmful substances.

 

The air-conditioned helmets

They protect the head, face, ears, and neck at the same time.  They are distinguished according to the way they rest on the body, that is on the shoulders or the head:  this is a significant peculiarity for a correct choice, according to the physiognomy of the operator, especially concerning the correct discharge of the weight of the device, so that it adheres well to the body, in order to avoid infiltration of polluted external air.

They can be classified into two macro-categories, according to the breastplate, which can be flexible, or semi-rigid.  In the first case, the lower end is made of waxed fabric and covers the neck and part of the shoulders. In this case, particular care must be taken to ensure that the cover adheres correctly to the shoulders, to prevent the entry of contaminated air. Conversely, the semi-rigid breastplate consists of an inner collar, which insulates the neck and must be correctly positioned without creating discontinuity with the protective suit, and an outer cover that is kept taut by elastic bands, allowing optimal insulation of the operator. 

While guaranteeing a high level of protection of the whole head from contact with harmful substances, the helmets highlight some critical points, such as not always optimal visibility, especially on the sides and when the head is rotated.   This is particularly important for operators when carrying out phytosanitary treatments because it is necessary to frequently check that the sprayer, which is mounted at the rear of the tractor, is working correctly.

The equipment supplied with the helmets is usually battery-powered or is connected directly to the tractor's electrical system. For this purpose, some models are equipped with a lap belt containing the battery pack and air regulator, and in some cases also the filters. Otherwise, some manufacturers offer models in which all the main parts are integrated into the helmet, with the advantage of being able to ensure a certain freedom of movement to the operator wearing it. 


The filters

The filters accompany masks, semi-masks and helmets; they must be certified, according to dedicated regulations, as category III devices. It is usually the combination of a pre-filter, which captures coarse dust, and employing a felt layer, dehumidifies the incoming air, and an activated carbon filter which reacts chemically with the chemical principle to be blocked. The devices differ in morphology, field of action, and scope of use. The filtering characteristics are coded by an abbreviation, whi­ch includes numbers, letters, and colors. Several filters can be combined to obtain a more complete filtering capacity. Filters must be scrupulously maintained to avoid clogging and loss of filtering efficiency. They have an expiry date, and the manufacturer provides specific replacement routines.

 

 

by Lavinia Eleonora Galli

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